The present invention is related to the assembly of microelectronic, photonic, and optoelectronic devices.
Flip-chip assembly of an edge-emitting laser chip (e.g., an indium phosphide (InP) laser chip) on another photonic chip (e.g., a silicon (Si) photonic chip), requires an edge of the laser chip to touch waveguides of the Si photonic ship. Such optical alignment between the laser chip and the Si photonic chip requires accuracy below 1 μm in three dimensions. This alignment is achieved via the surface tension of solder between the laser chip and the other photonic chip when the solder is melted during assembly.
If solder volume is not large enough, it is difficult to get good laser chip movement for self-alignment into a final position. This is so, because the friction force of the chip's surface and a standoff is bigger than a self-alignment force using solder surface tension. If there is too much solder to get a high force of X and Y-axis self-alignment, Z-axis alignment is not possible because the solder joint lifts the chip above the standoff. Accordingly, there is a need to minimize the friction for three-dimensional alignment.
In addition, when placing several laser chips on a single Si photonics substrate, the already placed chips can adversely move while a new chip is placed. Accordingly, there is a need to hold the already placed chips, while the next chips are placed. Also, all placed laser chips are required not to be moved during handling and belt reflow processes until the self-alignment is finished.